1. Field of the Invention
The invention relates to air filters, particularly portable air filtration apparatuses intended to filter dust in industrial and commercial establishments.
2. Description of Related Art
Many types of air filtration apparatuses have been developed for use in commercial and industrial establishments such as autobody repair shops. Some such units include a horizontally extending overhead duct where the final filtering is performed and from which the air is discharged downwardly. The air then picks up dust particles and is subsequently recirculated by being drawn into the intake of the unit.
Some such filtering apparatuses use rigid ducts which are hung from hangers connected to the ceiling. There are also portable units where the horizontal duct is permanently attached to the filtering apparatus.
Some prior art apparatuses are inconvenient in that they must be permanently installed and therefore cannot be moved about to different positions as required. Some portable units are relatively expensive and do not offer maximum recirculation of air because the reach of the horizontal duct carrying the overhead filter is relatively limited.
U.S. Pat. No. 5,163,985 to Chen shows a movable industrial dust collector having a filtration bag which extends upwardly from the unit. However, the bag is required to act as a filter and thus cannot function optimally to diffuse the air discharged from the unit.
Accordingly, it is an object of the invention to provide an improved filtering apparatus for autobody shops and the like which provides for recirculation of the air, but does not require permanently installed, horizontal overhead ducts.
It is also an object of the invention to provide an improved filtering apparatus of the type where the air from an overhead duct can be discharged downwardly at an appreciable distance away from the fan body of the unit.
It is a further object of the invention to provide an improved filtering apparatus of this type which is relatively simple and economical, but offers improved performance over prior art apparatuses.